Jumper clamps and jumper locking clamps for securing current carrying jumper cables to conductors are well known. Existing jumper locking clamps typically comprise a tubular housing having a threaded portion into which a threaded jumper head is screwed. The tubular housing may be a hollow cylindrical tube or body with an internal recessed area that securely accepts a threaded insert which defines a threaded orifice or aperture. The jumper head typically has an upper curved portion that conforms to the shape of a conductor and a lower threaded portion. The jumper head rests on the conductor while the threaded jumper head is threadedly received by the threaded portion of the tubular housing during installation. The threaded jumper head is electrically connected to a jumper cable or conductor.
During normal operation, existing jumper locking clamp designs typically encounter unintentional loosening of the locking clamp due to thermal cycling, mechanical vibration or other physical shocks on the conductor experienced during normal use. The loosening can result in a hazardous condition due to poor electrical connections between the loosened jumper locking clamp and the conductor.
Existing methods employed to mitigate these drawbacks include re-tightening or over-tightening the jumper locking clamp to prevent or minimize unintentional loosening. However, over-tightening can deform or damage the current carrying conductor, electrical insulation, or tubular housings. Also, over-tightening can cause the jumper locking clamp to stick or seize, requiring the use of special tools to assist in the subsequent removal of the jumper locking clamp which leads to increased removal time. Further, although over-tightening remedies unintentional loosening problems in the short term, unintentional loosening still occurs in the long term which results in hazardous or unsafe conditions, e.g., at installations or facilities that have long intervals between servicing and maintenance. Thus, re-tightening or over-tightening does not adequately address problems of unintentional loosening of existing jumper locking clamp designs, it only delays the onset of unintentional loosening of the jumper locking clamp.
There is thus a need for an improved jumper locking clamp design that prevents unintentional loosening of the jumper locking clamp due to vibration, thermal cycling or physical shock while still enabling easy installation and removal of the jumper locking clamp.